public class StudentCard {
    private String cardNumber;
    private String studentId;
    private String studentName;
    private double balance;
    public StudentCard(String cardNumber, String studentId, String studentName, double balance) {
        this.cardNumber = cardNumber;
        this.studentId = studentId;
        this.studentName = studentName;
        this.balance = balance;
    }
    public StudentCard(String cardNumber, String studentId, String studentName) {
        this.cardNumber = cardNumber;
        this.studentId = studentId;
        this.studentName = studentName;
        this.balance = 0;
    }
    public void printCardInfo() {
        System.out.println(cardNumber + ", " + studentName + ", " + studentId + ", " + balance);
    }

    public static class StudentCardTest {
        public static void main(String[] args) {
            StudentCard card1 = new StudentCard("2554441", "202255446", "张三", 100.5);
            card1.printCardInfo();
            StudentCard card2 = new StudentCard("2515122", "202255421", "李四");
            card2.printCardInfo();
        }
    }
}

